Background: Eating “sirih/Betel” (Ngeu Nata) as a culture in Ngada society can become one of the primary source of Tuberculosis (TB) transmission due to share leaves and betel liquid reservoirs together with other people. If one of the people who share leaves is a TB patient, it can transmit TB to other person. The purpose of this study was to identify the factors that influence TB transmission in Ngeu Nata culture using the health belief model approach. Design and Methods: This study used cross-sectional, involving 110 respondents, selected by consecutive sampling. The respondents were Bajawa ethnicity, age 36-67, at least consume Betel one a day together with other person in Ngada district, East Nusa Tenggara. Results: The results showed that most respondents had high transmission behavior in betel eating culture (51.8%). Factors related to TB transmission behavior: medical history of TB (p=0.028), knowledge about TB (p=0.038), the perceived of severity of TB (p=0.037); the perceived of benefits (p=0.039) and the perceived of barrier (p=0.038). The dominant factor was knowledge, (OR 2,365 (95% CI) 1,015-5,510). Conclusions: Implication: nurses should include aspect of Ngeu Nata cultural in designing TB education for Bajawa ethnicity in order to prevent TB transmission in Ngada district, East Nusa Tenggara. © 2021, Page Press Publications. All rights reserved.